1. Field of the Invention
This invention pertains generally to tool posts for machine tools such as lathes and the like and more particularly to an improved tool post mechanism for supporting a plurality of tool holders each having metal working tools, with the tool post capable of being locked at a selected position with respect to a moving, typically rotating work-piece and capable of being unlocked and rotatable to a selected rotary position to operatively position any selected metal working tool thereof in desired working orientation with respect to the work-piece. More particularly, the present invention concerns a quick-change tool post having a single actuating handle which achieves unlocking of an indexing mechanism during a first rotational increment of handle movement and achieves rotation of the tool post to a selected position during another increment of rotational movement, followed by achieving locking of the tool post at the selected position upon an opposite increment of rotational movement. Even further, the present invention concerns a quick change tool post having internal channels for coolant flow controlling capability and having laterally off-set dovetail connections enabling connection of standard rectangular tool supports thereto.
2. Description of the Prior Art
A variety of tool posts have in the past been evolved which hold a plurality of tool holders in which tools for operation on a workpiece held on a machine tool such as a lathe, may be held. Such previously evolved multiple tool holding tool posts have served to increase the speed and facility with which any given machining operation may be performed in that the setup time for positioning any given tool with respect to a workpiece may be minimized.
The present inventor""s U.S. Pat. No. 4,126,067 is an example of a quick-change indexing tool post for supporting a plurality of metal working tools and for enabling rapid selective positioning of any selected one of the metal working tools in operative metal working relation to a workpiece that is movably, i.e., rotatably supported on a machine tool such as a lathe.
As shown in FIG. 1 of applicant""s U.S. Pat. No. 4,126,067 in order to enable four tool holders to be mounted to the tool post, lateral edges of each of the tool holders must be beveled at the edges thereof at an angle of 45 degrees so that a tool holder can be mounted to each tool support, face of the tool post and adjacent tool holders will not interfere with one another. Thus, special tool holders are required for this particular type of tool post.
It is well known that virtually that all machine shops operating in the United States at the present time have a number of conventional xe2x80x9crectangularxe2x80x9d tool holders which, because of their size and rectangular configuration, cannot be mounted to the tool post body shown in applicant""s prior patent. It is desirable therefore to provide a tool post construction which enables conventional rectangular tool posts to be mounted to the tool post body, thus enabling machine shops to make wide use of conventional rectangular tool holders and thus minimizing the inventory requirements that might otherwise be necessary to enable wide use of quick-change tool posts of this nature. The conventional rectangular tool holders typically have a width from side to side, substantially equaling the width of a rectangular tool post body or the width of a tool supporting face of a tool post for supporting multiple metal working tools. Thus, for mounting the rectangular tool holders to the bed of a machine tool, the tool holders must be beveled at the sides, must be of narrow width or the tool post structure must be of exceptionally large size. Any of these possibilities would be detrimental to the cost and structural integrity of the tool supporting components of the machine tool or tool post. Thus, it is considered desirable to provide a tool post construction of relatively small dimension, i.e., having tool support faces of no greater width that the width of standard tool holders and yet being capable of supporting a metal working tool at each of the multiple tool support faces of the tool post. It is also desirable to provide a tool post mechanism having a generally rectangular tool post body having four tool support faces each having a dovetail connection and being capable of supporting four rectangular tool support elements each having substantially the same width as the tool post body and having a mating dovetail connection to achieve mounting thereof.
Since virtually all machining operations require the presence of a coolant liquid which is continuously applied to the cutting tool and to the work-piece being movably supported by the machine, to thus prolong the active service life of the metal working tool being utilized and to minimize machining vibration. Though most machining operations are provided with coolant supply conduits, these conduits must be individually oriented typically by a manual operation to enable adequate supply of coolant intimately to the metal working site. Also, when indexing tool posts are employed during machining, the machinist must reposition the coolant supply conduit each time the tool post is rotated to a new position. This disadvantage adds significantly to machine time and thus adversely influences machining costs. At times, machinists manually adjust the position of the coolant supply conduits during operation of a machine and thus get hands, arms and clothing dangerously close to the rotating work-piece, thus presenting a safety hazard. It is desirable therefore, to provide a tool post construction having a coolant supply system which automatically, without any manual selection or positioning activity of the machinist, delivers a supply of coolant only to a selected metal working tool and which is oriented precisely to the metal working operation of any selected metal working tool supported thereby.
Most present day tool post designs, in order the achieve rotation of the tool post to position a selected tool in operative relation with the work piece, require that the tool post initially be unlocked and then require that the tool be manually rotated to a selected position. Typically, the tool post is unlocked by first loosening a locking nut and then rotating a locking handle of an indexing head to an unlocked position. After this has been done, the tool post may then be selectively and manually rotated to a desired position, after which the tool post is again locked by rotating the locking handle in an opposite rotary direction for locking the tool post and securing it in immovable relation with the bed of a machine tool. Thus, for unlocking, rotating and relocking the tool posts, multiple manual movements are required on behalf of the machinists and a considerable amount of machine down time is also required to achieve selective positioning of a metal working tool being supported by the tool post. It is desirable, therefore, to provide an improved tool post design which enables the tool post to be unlocked and rotated to a selected position by a single rotational movement of a locking handle or ratcheted to a desired position by successive ratcheting movements of an actuating handle and then again locked by rotating the locking handle in the opposite rotational direction. This xe2x80x9cone-handxe2x80x9d locking, positioning and relocking procedure can be done quite rapidly, thus materially enhancing the productivity of the machining operation that is being done.
Many quick-change tool posts are provided with xe2x80x9cexternalxe2x80x9d indexing mechanisms where portions of the indexing splines protrude beyond the lateral tool support faces of the rectangular tool post body. In these cases, the tool holders that are to be releasably mounted to the dovetail mounting connections must have cut-outs that enable the tool holders to clear the protruding edges of the indexing mechanism or its enclosure. The standard rectangular tool holders that are typically present in large numbers in virtually every machine shop cannot be fully assembled to these types of tool posts because of the protruding edge portions of the indexing mechanism. Thus xe2x80x9cspecialxe2x80x9d tool support devices are required, which have cutouts for the protruding portions of the external indexing mechanism. These cutouts obviously weaken the structural integrity of the tool supports, so that the tool supports are less rigid as compared with the rigidity or structural integrity of standard rectangular tool holders. This shortcoming becomes especially critical or important when the metal working tool supported thereby is engaged in making a heavy roughing cut on the work-piece. It is desirable therefore to provide a tool post mechanism which has an internal indexing mechanism, thus eliminating the need for special tool supports having cutouts and facilitating the use of standard rectangular tool supports which are adapted for full length dovetail engagement with the dovetail mounting connections of the tool post body.
It is therefore a principal feature of the present invention to provide a novel quick-change tool post mechanism having laterally offset dovetail connections which enable the use of standard rectangular tool supports so that the tool support inventory of machine shops can be minimized;
It is another feature of the present invention to provide a novel quick-change indexing tool post mechanism having an indexing system permitting unlocking and selective rotation of the tool post to a desired operating position by rotational movement of a locking handle in a single rotational direction followed by locking of the tool post mechanism at the selected position by opposite rotation of the locking handle so that unlocking, rotation and relocking of the tool post can be accomplished by one-handed operation of the machinist using the metal working machine.
It is also a feature of the present invention to provide a novel quick-change indexing tool post mechanism having a coolant supply system which conducts a flow of coolant liquid in a manner directing the coolant to the site of the metal working tool that is selected by rotary positioning of the tool post mechanism;
It is another feature of the present invention to provide a novel quick-change indexing tool post mechanism having an internal indexing mechanism and thereby enabling the various tool support devices in assembly therewith to be of maximum rigidity so that the metal working tool supporting thereby is as stable as possible during the metal working operation.
Briefly, the various objects and features of the present invention are realized by providing a generally rectangular tool post body which is specifically designed to receive standard, rectangular tool supports. The tool post body defines a plurality, typically four, generally planar tool support faces having essentially the same width and the width of standard rectangular tool holders. The tool post body at each of the tool support faces defines a first dovetail tool mount connection which is typically an external dovetail connection, though internal dovetail connections may be employed if desired. The generally rectangular tool mounting faces of the tool post body each define centerlines that are oriented and generally parallel relation with the centerline of the holding post about which the tool post body is mounted for rotation. The dovetail tool mount connections which are defined by each of the tool support faces of the tool post body each define dovetail face centerlines that are offset laterally with respect to the mounting face centerlines of the tool post body so that standard, rectangular tool supports may be assembled to the tool post body with one of the sides thereof extending beyond a respective side of the tool post body and disposed in overlapping relation with the side of an adjacent conventional rectangular tool support. This feature permits each of the tool supports to be of standard rectangular character and to have maximum structural integrity and rigidity to thereby provide for optimum support of each of the metal working tools being supported by the respective tool support devices. Moreover, the quick-change indexing tool post mechanism of the present invention is provided with an internal interengaging spline type indexing mechanism so that no portion of the indexing splines or indexing elements protrude the tool mounting faces of the rectangular tool post body or beyond the dovetail connections. Thus, the tool support elements are not required to have cutouts and standard, rectangular tool supports may be utilized which establish full length dovetail interconnection with the dovetail connection mounts of the tool post body.
In the preferred embodiment of the present invention, the centrally located holding post of the quick-change tool post mechanism is provided with a longitudinal coolant supply channel which is in communication with the pressurized coolant supply of the machine tool. Other components of the quick-change tool post mechanism, such as the sleeve type indexing post and the indexing head, define coolant ports and channels which establish communication with the coolant supply channel of the holding posts so that coolant is supplied only to a selected metal working tool at any point in time. Moreover, the supply of coolant to the selective metal working tool is automatic upon selective positioning of the tool post body and thus does not require any manual time consuming activity on the part of the machinist using the machine tool.
The tool post body is provided with an indexing recess at its bottom portion which receives a top spline element which is fixed to the tool post body and a bottom spline element which is retained in non-rotatable assembly with the sleeve type indexing post. A stack of disc springs is interposed between the bottom spline element and the tool post body to continuously urge the bottom spline toward a direction of separation from the top spline. The top and bottom splines are maintained in inter-engaging relation by a locking or actuating nut which is in threaded engagement with threads of the indexing post and which bears against an indexing head that is fixed to the tool post body. The locking nut is provided with a locking handle which is rotated to impart rotational locking or unlocking movement to the locking nut. During the rotary unlocking movement the locking nut is driven counter-clockwise, thus permitting the disc springs to shift the tool post body and its top spline upwardly, thus separating the top spline from the bottom spline and positioning the splines out of locking engagement. After this unlocking movement has occurred, continuing movement of the locking handle through a second increment of rotary movement, achieves rotary positioning of the tool post body so as to position a selected metal working tool in operative relation with the moving work piece. After such positioning, the locking handle is actuated to accomplish rotary movement of the locking nut in the clockwise direction thereby driving the indexing post upwardly relative to the tool post body and forcing the top and bottom splines to establish inter-engaging locking relation against the mechanical bias of the disc springs.
Each of the dovetail connections of the tool post body defines a wedge or gib receptacle within which is located a dovetail expansion plate or gib element. Each of the dovetail connections is also provided with a rotary gib actuator having an eccentric surface in contact with the gib element. As the rotary actuator is rotated, typically by an Allen wrench, the gib element is moved linearly, thereby expanding the dovetail connection and locking the respective tool holder firmly and securely to the tool post body. The mechanical force generated by the eccentric surface on the gib element is effective to prevent movement of the tool support element relative to the tool post body even when the tool is engaged in heavy, rough metal cutting operations.
So that the manner in which the above recited features, advantages and objects of the present invention are attained and can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to the preferred embodiment thereof which is illustrated in the appended drawings, which drawings are incorporated as a part hereof.
It is to be noted however, that the appended drawings illustrate only a typical embodiment of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments.